Electric rivet-heater



F. T. Km. ELECTRIC RIVET HEATER.

APPLICATION FILED AUG1Z6|191L I Patented Apr. 12, 1921.

INVENTOR 30 1 Figure 1 shows a vertical section .of my UNITED sTATEs PATENT OFFICE;

FREDERICK "r. KITT, or SEATTLE, WASHINGTON, Ass'IGNoR, BY MESNE AssIeN- MENTS, T0 AMERICAN can AND FOUNDRY CQMPANY, or NEW YORK, N,

. A CORPORATION OF NEW JERSEY.

- ELECTRIC, RIV'ET-HEATER.

To all whom it may concern;

Be it known-that I, FRE ERICK Kri'r, a

resident of Seattle, county of King, and

State of Washington, have invented a new and useful Improvement in Electric Rivet Heaters, of which the following isa' full and complete description; reference be ng had to the accompanyingdrawlng, forming a part 'a'rivet heater having j'awsv adapted to receive rivets of different lengths when opened and closed by ual movements of a predetermined lengtll. It further has for its object to provi e a rivet heater in whlch the opening and closing is b'rought.'about by a relative angular movement of the jaws, It

furtherhas .for its object to provide a transformer rivet'heater having a new and 1m- .proved construction for securing the cooling of the" transformer when in operation. It further has for its object to provide an r ,effioient 'blast for assisting in s'uch'cooling.

.Itfurther has for-its object to provide a means ffor. securing better. contact between the jaws and the rivet to be heated The following is a descrlption .of an em bodiment of my invention, reference-being had to the accompanying drawlngs, n-

which,

' apparatus, on a plane parallel to the primary and secondary winding;

Fig. 2 is a front view of the apparatus Fig. 3 is'a plan view ofthe same; and, Fig. 4 is a sectional detail of the jaws iholdingthe rivet whilebeing heated.

rivets do. not require as much power as larger ones, besides the voltage of the source Referring more particularly to' the drawings, P represents the primary of a trans-" former 'I the laminated iron magnetic circuit, and S a single-turn secondary placed around the primary and approximately surrounding the same, all shownin cross-secis used in order to form convenient means,

whereby the heating of'the rivets may be regulated by supplyinga greater or-smaller amount of power,as it 1s obvious that small I Specification of Letters Iatent. Pate t d A 1 1921. Application filed August 26, 1919. Serial No. 319,933, v

of supply may vary, which variation can be compensated for by means of the. switch B.

L representsfla number of conductors or leads which are tappedintothe primary 'coils at certain points and broughtout to the contacts 0 at the base of the switchB. L represents. a lever pivoted at P which the conductor L. LL is another conductor leading from thecoil -P to the line of source of alternating current supply L the other side of the source of supply being connected, as shown in Fig. 3, to one point of the switch D. 1th the-switch D in closed position, as shown, current will flow from one line L to .thepoint P and thence through lever L is being heated,rand is preferably made up of two or more pieces of copper bars bent so asto approxlmately encircle the primary B and welded at the points W to castor forged I copper jaws J. and J A represents two straps of copper or other suitable material also welded to the secondary, the purpose of which is to hold all the units together firmly and to form a means of fastening the entire assembly of secondary'members to the metal frame F, which, together with F, formsthe supports'between which the iron core of the transformer is clamped. It will be noted that the secondary is fastened or suspended .only at this point, which is an important feature as will be-pointed out later.

The rivet R, which it is desired to heat, is

placed bet-ween the jaws J, J as shown, thus completing the secondary circuit and allow- .ing a. large volume of current at a very low voltage to flow, which quickly heats the rivet .to the temperature necessary for driving the same. A rod H is connected to the jaw J, asshown, and j extends down through an insulating block F which rests upon the frame F, as shown in Fig. 2. Between-this block F and the enlarged upper portion of H, forming an abutment, is a strong compression spring E, which tends to force the point is connected to a switch D by means of tends to a convenient foot lever, which I have not deemed it necessary to show.

placing the rivet into the jaws to be heated, the foot lever is pressed down, overcoming the tension of the spring E and forcing the jaws apart and the rivet is then placed as shown and the foot lever released, which causes a pressure to be placed uponthe rivet, securing. good contact between its ends and the copper jaws J, J.

VVhe-n the rivet has been sufiiciently heated it is removed by again depressing the foot lever, which releases the tension, breaks the electrical contact and enables the operator to lift the rivet out with his tongs.

It will be obvious to any one skilled in the 'art that avery large amperage is requiled to heat a rivet, also that the handling of so large a volume ofcurrent makes it necessary that every possible resistance to its {101W be eliminated in order that practically all the power will be expended in heating the rivet instead of heating other parts of the circuit.

It is: also well known that joints or bolted connections which must carry a heavy current at a low voltage are very troublesome on account of their high resistance, and for that reason I have eliminated everything of that nature in the secondary, and in order that different lengths of rivets may be heated without making it necessary to make mechanical adjustments, I have developed what might be termed alligator aws, as shown,

the same consisting of two elongated jaws whose outer ends are spaced farther apart than their inner ends. In the construction shown the inner surfaces of the aws are at an acute angle to. one another and their relative movement is somewhat angular.

With this form of aw or. electrode any size of rivet may be heated, within the limits for which the particular machine is de- Signed, by. simply placing it within the jaws as far as it will go, the opening and closing v of the jaws for any size of rivet requiring movements of an equal predetermined length. A long rivet will be placednear the outer ends of the jaws, while a shorter one will be placed farther in toward the throat. One of the jaws, preferably the lower one, is horizontal while the other extends out at an acute angle, as shown.

If the faces of these jaws were both flat 'it is obvious that the upper end of the rivet would be in contact with theelectrode on one side only, which would cause the rivet to heat unevenly as: the greatest heat is at the In order to eliminate this Fig. 4:, which represents a cross-section taken on the line 4 in Fig. 1. It will be noticed that no matter how great the angle is between the jaws, the upper one will make conh and h. In.

vertical planepassing through the longitudinal axes of saidtwo electrodes.

The object of holding the secondary to the frame F is two-fold: First, it forms a-single point of suspension andenables the secondary to gradually bend from point A to the jaw J when the foot lever-is pressed down, making any oint or hinge unnecessary; second, it provides a. means of conducting the heat of the secondary to the frameof the machine throughwhich it is dissipated by a natural ventilation and enables it to be spaced from the primary.

In order to prevent overheating of the primary 'B, I have provided an air space between the primary and secondary, which makes a water-cooling system unnecessary. Under ordinary conditions, the natural radiation is sufficient, but under extra hard service conditions it may be necessary to stimulate the radiation, and for that purpose I have provided an air nozzle .C consisting of a pipe aflixed to the frame F ap proximately in the position shown, adjacent to the throat of the jaws and connected to a source of compressed air or a blower. On the lower surface of this pipe C I provide a series of holes or a'slot through which a volume of air can be forced between the primary and secondary, which will take the course indicated by the arrows. The air when first ejected flows downward and then to the rear, whereupon, having become heated, it rises through the succeeding. vertical portion of the passage, then passes forward and is discharged from the throat between the jaws. This, together with the natural radiation as above mentioned, has proven ample for any conditions met with in practice,

The advantages of heating rivets by this method is reat efficiency and consequently very greatly reduced cost, the absence of any harmful gases given off by an open flame and the elimination of dirt and ashes, all of which is a great consideration, especiallyaboard ships either building or being repaired. The lesser risk of fire is also a great advantage, especially on boats, or in other places where riveting hasito be done near inflammable substances.

As will be evident to those skilled in the art, my invention permits of various modifications without departing from the spirit thereof or the scope of theappended claims.

Having thus described my invention, what I claim is;

1. In an electric rivet heater, the combination of a magnetic core, a primary winding upon the'same, a secondary in inductive relation thereto, relatively movable terminal jaws connected to said secondary, the opposing faces of the front ends of said jaws being farther separated than the inner portions thereof, and means for varying the distance between said jaws.

2. In an' electric rivet heater, the combination of a magnetic core, a primary winding upon the same, a secondary in inductive I relation thereto, terminal jaws connected to said secondary capable of relative angular movement, the opposing faces of the front ends of said jaws being farther separated than the inner portions thereof, and means for varying the angle between said jaws;

3. In an electric rivet heater, the combination of electrodes for holding rivets and having V-surfaces in order to insure elec trical contact at two points of the rivet end, as shown and described.

4. In an electric rivet heater, the combination of two electrodes having a relative movement and adapted to hold rivets, the

opposing surfaces of said electrodes approachingone another on each side of a vertical plane passing through the longitudinal axes of said electrodes.

FRED. 'r. KITT. 

